diff --git a/src/components/CodeLookup/CodeLookup.stories.tsx b/src/components/CodeLookup/CodeLookup.stories.tsx
index 4fb510b8..c5e76995 100644
--- a/src/components/CodeLookup/CodeLookup.stories.tsx
+++ b/src/components/CodeLookup/CodeLookup.stories.tsx
@@ -1,6 +1,10 @@
 import type { Meta, StoryObj } from '@storybook/react-vite';
 import { useState } from 'react';
-import { CodeLookup, type CodifyDomain } from './CodeLookup';
+import {
+  CodeLookup,
+  type CodifyDomain,
+  type CodetypeOption,
+} from './CodeLookup';
 import type { CodifyResult } from './engine';
 
 const meta: Meta<typeof CodeLookup> = {
@@ -50,10 +54,14 @@ type Story = StoryObj<typeof CodeLookup>;
 function Template({
   domains,
   searchDomains,
+  searchCodetypes,
+  codetypeOptions,
   locale,
 }: {
   domains?: CodifyDomain[];
   searchDomains?: CodifyDomain[];
+  searchCodetypes?: string[];
+  codetypeOptions?: CodetypeOption[];
   locale?: string;
 }) {
   const [selected, setSelected] = useState<CodifyResult | null>(null);
@@ -64,6 +72,8 @@ function Template({
         locale={locale}
         domains={domains}
         searchDomains={searchDomains}
+        searchCodetypes={searchCodetypes}
+        codetypeOptions={codetypeOptions}
         onSelect={setSelected}
       />
       {selected && (
@@ -82,11 +92,38 @@ export const AllDomains: Story = {
 
 /** Conditions only (ICD-10 + SNOMED, ~14 MB). Try "con hea fa", "chf", "lvhf".
  * Results collapse to one row per condition family (ICD-10 code root); → lists
- * the specific billable codes. Planned: the drill-down will also surface
- * suggested orders (labs/procedures) for the condition. */
+ * the specific billable codes. The segmented control lets the user restrict
+ * the coding system (`codetypeOptions`); a fixed programmer-set filter is the
+ * `searchCodetypes` prop instead (see "Conditions ICD-10 Only"). An ICD-11
+ * option is one `{ label: 'ICD-11', codetypes: ['ICD11'] }` away once the
+ * shards carry ICD-11 rows (the source dataset has none yet). Planned: the
+ * drill-down will also surface suggested orders (labs/procedures) for the
+ * condition. */
 export const ConditionsOnly: Story = {
   render: (_args, { globals }) => (
-    <Template domains={['condition']} locale={globals.locale} />
+    <Template
+      domains={['condition']}
+      codetypeOptions={[
+        { label: 'All' },
+        { label: 'ICD-10', codetypes: ['ICD10'] },
+        { label: 'SNOMED', codetypes: ['SNOMED US'] },
+      ]}
+      locale={globals.locale}
+    />
+  ),
+};
+
+/** Programmer-fixed coding system: `searchCodetypes={['ICD10']}` — SNOMED
+ * synonyms never appear, no user toggle. Swap in `['ICD11']` when the shards
+ * include ICD-11. */
+export const ConditionsIcd10Only: Story = {
+  name: 'Conditions ICD-10 Only',
+  render: (_args, { globals }) => (
+    <Template
+      domains={['condition']}
+      searchCodetypes={['ICD10']}
+      locale={globals.locale}
+    />
   ),
 };
 
diff --git a/src/components/CodeLookup/CodeLookup.tsx b/src/components/CodeLookup/CodeLookup.tsx
index 8deb87fb..69e905e3 100644
--- a/src/components/CodeLookup/CodeLookup.tsx
+++ b/src/components/CodeLookup/CodeLookup.tsx
@@ -36,6 +36,14 @@ export type CodifyDomain =
   | 'occupational'
   | 'quality';
 
+/** One choice in the user-facing coding-system filter (`codetypeOptions`). */
+export interface CodetypeOption {
+  /** User-visible label (externalize/translate in the consumer), e.g. 'ICD-10' */
+  label: string;
+  /** Coding systems this option restricts to (e.g. ['ICD10']); omit for "all" */
+  codetypes?: string[];
+}
+
 export interface CodeLookupProps extends Omit<
   React.HTMLAttributes<HTMLDivElement>,
   'className' | 'onSelect'
@@ -78,6 +86,20 @@ export interface CodeLookupProps extends Omit<
    * and SNOMED entries are dropped. Other domains are unaffected.
    */
   billableOnly?: boolean;
+  /**
+   * Restrict results to these coding systems at query time (e.g. ['ICD10']
+   * for an ICD-10-only picker; ['ICD11'] once the shards carry ICD-11 rows).
+   * Applies to the drill-down too. Ignored while `codetypeOptions` is
+   * rendered — the user's pick wins.
+   */
+  searchCodetypes?: string[];
+  /**
+   * Let the user pick the coding-system filter: renders a segmented control
+   * above the search box. The first option is selected initially — give it
+   * no `codetypes` for "all systems". E.g.
+   * `[{ label: 'All' }, { label: 'ICD-10', codetypes: ['ICD10'] }]`.
+   */
+  codetypeOptions?: CodetypeOption[];
   /** Called when a result is picked */
   onSelect?: (result: CodifyResult) => void;
   /**
@@ -173,6 +195,8 @@ export const CodeLookup = React.forwardRef<HTMLDivElement, CodeLookupProps>(
       preferDomains,
       preferCodetypes,
       billableOnly = false,
+      searchCodetypes,
+      codetypeOptions,
       programsUrl,
       onSelect,
       onFreeText,
@@ -228,6 +252,22 @@ export const CodeLookup = React.forwardRef<HTMLDivElement, CodeLookupProps>(
     const preferCodetypesKey = preferCodetypes
       ? preferCodetypes.join(',')
       : null;
+    // coding-system filter: the user's segmented-control pick (when
+    // codetypeOptions is rendered) overrides the searchCodetypes prop. Guard
+    // against an empty options array (falls back to searchCodetypes) and an
+    // index left past the end when the options shrink.
+    const [codetypeIdx, setCodetypeIdx] = React.useState(0);
+    const hasCodetypeOptions = (codetypeOptions?.length ?? 0) > 0;
+    const activeCodetypeIdx = hasCodetypeOptions
+      ? Math.min(codetypeIdx, codetypeOptions!.length - 1)
+      : 0;
+    const activeCodetypes = hasCodetypeOptions
+      ? codetypeOptions![activeCodetypeIdx]?.codetypes
+      : searchCodetypes;
+    const codetypesKey = activeCodetypes ? activeCodetypes.join(',') : null;
+    /** active codetypes for the stable openDrill callback */
+    const codetypesRef = React.useRef(activeCodetypes);
+    codetypesRef.current = activeCodetypes;
 
     React.useEffect(() => {
       // A new worker starts from scratch — reset all search state so a stale
@@ -325,6 +365,7 @@ export const CodeLookup = React.forwardRef<HTMLDivElement, CodeLookupProps>(
           domains: keyToDomains(searchDomainsKey),
           prefer: keyToDomains(preferDomainsKey),
           boostCodetypes: keyToDomains(preferCodetypesKey),
+          codetypes: keyToDomains(codetypesKey),
           billableOnly,
           // one row per med family; variants live in the → drill-down
           collapse: true,
@@ -338,6 +379,7 @@ export const CodeLookup = React.forwardRef<HTMLDivElement, CodeLookupProps>(
       searchDomainsKey,
       preferDomainsKey,
       preferCodetypesKey,
+      codetypesKey,
       billableOnly,
     ]);
 
@@ -370,6 +412,7 @@ export const CodeLookup = React.forwardRef<HTMLDivElement, CodeLookupProps>(
         query: familyTerm(parent.domain, parent.label) || parent.label,
         limit: 300,
         domains: [parent.domain],
+        codetypes: codetypesRef.current,
         billableOnly: billableOnlyRef.current,
       });
     }, []);
@@ -462,6 +505,74 @@ export const CodeLookup = React.forwardRef<HTMLDivElement, CodeLookupProps>(
       HTMLDivElement
     >({ open: dropdownOpen, matchWidth: true });
 
+    // user-facing coding-system filter (e.g. All | ICD-10 | SNOMED)
+    const codetypeBtnRefs = React.useRef<(HTMLButtonElement | null)[]>([]);
+    const selectCodetype = (i: number) => {
+      setCodetypeIdx(i);
+      setDrill(null);
+    };
+    // ARIA radiogroup keyboard model: arrows/Home/End move selection and
+    // focus (roving tabIndex); only the checked radio is in the tab order.
+    const onCodetypeKeyDown = (
+      e: React.KeyboardEvent<HTMLButtonElement>,
+      i: number
+    ) => {
+      const n = codetypeOptions!.length;
+      let next: number;
+      switch (e.key) {
+        case 'ArrowRight':
+        case 'ArrowDown':
+          next = (i + 1) % n;
+          break;
+        case 'ArrowLeft':
+        case 'ArrowUp':
+          next = (i - 1 + n) % n;
+          break;
+        case 'Home':
+          next = 0;
+          break;
+        case 'End':
+          next = n - 1;
+          break;
+        default:
+          return;
+      }
+      e.preventDefault();
+      selectCodetype(next);
+      codetypeBtnRefs.current[next]?.focus();
+    };
+    const codetypeToggle = hasCodetypeOptions && (
+      <div
+        role="radiogroup"
+        aria-label="Coding system"
+        className="flex flex-wrap items-center gap-1"
+      >
+        {codetypeOptions!.map((opt, i) => (
+          <button
+            key={i}
+            ref={(el) => {
+              codetypeBtnRefs.current[i] = el;
+            }}
+            type="button"
+            role="radio"
+            aria-checked={i === activeCodetypeIdx}
+            tabIndex={i === activeCodetypeIdx ? 0 : -1}
+            onClick={() => selectCodetype(i)}
+            onKeyDown={(e) => onCodetypeKeyDown(e, i)}
+            className={cn(
+              'rounded-full border px-2.5 py-0.5 text-xs transition-colors',
+              'focus:ring-ring focus:ring-2 focus:outline-none',
+              i === activeCodetypeIdx
+                ? 'border-primary-800 bg-primary-800 dark:border-primary-400 dark:bg-primary-400 dark:text-primary-950 text-white'
+                : 'border-border text-muted-foreground hover:text-foreground'
+            )}
+          >
+            {opt.label}
+          </button>
+        ))}
+      </div>
+    );
+
     const searchBox = (
       <div className="relative" ref={anchorRef}>
         <SearchIcon
@@ -496,7 +607,6 @@ export const CodeLookup = React.forwardRef<HTMLDivElement, CodeLookupProps>(
             'focus:ring-ring focus:ring-2 focus:outline-none'
           )}
         />
-
         {/* floating dropdown — portaled so no ancestor can clip it */}
         {dropdownOpen &&
           createPortal(
@@ -638,10 +748,11 @@ export const CodeLookup = React.forwardRef<HTMLDivElement, CodeLookupProps>(
       return (
         <div
           ref={ref}
-          className={cn('w-full', className)}
+          className={cn('w-full space-y-2', className)}
           data-testid={dataTestId}
           {...props}
         >
+          {codetypeToggle}
           {searchBox}
         </div>
       );
@@ -657,6 +768,7 @@ export const CodeLookup = React.forwardRef<HTMLDivElement, CodeLookupProps>(
         {...props}
       >
         <CardContent className="space-y-2 px-4 py-4">
+          {codetypeToggle}
           {searchBox}
 
           {/* status line */}
diff --git a/src/components/CodeLookup/codify.worker.ts b/src/components/CodeLookup/codify.worker.ts
index 32fe6d24..27c2b629 100644
--- a/src/components/CodeLookup/codify.worker.ts
+++ b/src/components/CodeLookup/codify.worker.ts
@@ -321,6 +321,7 @@ self.onmessage = (e: MessageEvent) => {
     const collapse = msg.collapse === true;
     const opts = {
       boostCodetypes: msg.boostCodetypes as string[] | undefined,
+      codetypes: msg.codetypes as string[] | undefined,
       billableOnly: msg.billableOnly === true,
     };
     let results;
diff --git a/src/components/CodeLookup/engine.test.ts b/src/components/CodeLookup/engine.test.ts
index 62543b1e..b918339f 100644
--- a/src/components/CodeLookup/engine.test.ts
+++ b/src/components/CodeLookup/engine.test.ts
@@ -400,6 +400,33 @@ describe('searchShards', () => {
       expect(r[0].fullcode).toBe('E11.9');
     });
 
+    it('restricts label and code matches to opts.codetypes', () => {
+      const shard = makeShard('condition', [
+        { label: 'Heart failure', code: 'I50.9', codetype: 'ICD10' },
+        {
+          label: 'Heart failure (disorder)',
+          code: '84114007',
+          codetype: 'SNOMED US',
+        },
+      ]);
+      // label search
+      const labels = searchShards([shard], 'heart failure', 20, false, {
+        codetypes: ['ICD10'],
+      });
+      expect(labels).toHaveLength(1);
+      expect(labels[0].codetype).toBe('ICD10');
+      // code search
+      expect(
+        searchShards([shard], '8411', 20, false, { codetypes: ['ICD10'] })
+      ).toHaveLength(0);
+      // a shard with none of the requested systems yields nothing
+      expect(
+        searchShards([shard], 'heart failure', 20, false, {
+          codetypes: ['ICD11'],
+        })
+      ).toHaveLength(0);
+    });
+
     it('still finds the exact code among many prefix matches (scan cap)', () => {
       // 1500 codes share the prefix — beyond MAX_CODE_SCAN — but the exact
       // match sits at the start of the sorted range and is always scanned
diff --git a/src/components/CodeLookup/engine.ts b/src/components/CodeLookup/engine.ts
index ef1eff8e..9453061f 100644
--- a/src/components/CodeLookup/engine.ts
+++ b/src/components/CodeLookup/engine.ts
@@ -438,6 +438,10 @@ export interface SearchOptions {
   /** Multiply matching docs' scores by CODETYPE_BOOST (e.g. ['ICD10'] so
    * billing codes outrank SNOMED synonyms in an assessment context) */
   boostCodetypes?: string[];
+  /** Restrict results to these coding systems (e.g. ['ICD10'] for an
+   * ICD-10-only condition picker). Docs of other codetypes are dropped;
+   * shards containing none of them are skipped entirely. */
+  codetypes?: string[];
   /** Conditions: only billable (leaf) ICD-10 codes — category roots and
    * SNOMED entries are dropped. Other domains are unaffected. */
   billableOnly?: boolean;
@@ -447,6 +451,18 @@ export interface SearchOptions {
  * ICD-10 code outranks a shorter, leading-matched SNOMED synonym. */
 const CODETYPE_BOOST = 3;
 
+/** Shard-local codetype indices allowed by opts.codetypes (null = no filter;
+ * an empty set means the shard has none of the requested systems). */
+function allowedCodetypes(
+  s: CodifyShard,
+  opts?: SearchOptions
+): Set<number> | null {
+  if (!opts?.codetypes) return null;
+  return new Set(
+    opts.codetypes.map((ct) => s.codetypes.indexOf(ct)).filter((i) => i >= 0)
+  );
+}
+
 // =============================================================================
 // Code search — only label/alias words are tokenized in the shards, so a
 // typed code ("I50.9", "2345-7", "73211009") is matched by prefix against a
@@ -515,6 +531,8 @@ function searchShardCodes(
   }
   const billable =
     opts?.billableOnly && s.domain === 'condition' ? billableMask(s) : null;
+  const allowed = allowedCodetypes(s, opts);
+  if (allowed && allowed.size === 0) return;
   // codetype boost — same contract as searchShard (see SearchOptions)
   let boostIdx: Set<number> | null = null;
   if (opts?.boostCodetypes) {
@@ -527,6 +545,7 @@ function searchShardCodes(
   for (let i = lo; i < end && keys[i].startsWith(q); i++) {
     const d = docs[i];
     if (billable && billable[d] !== 1) continue;
+    if (allowed && !allowed.has(s.docCodetype[d])) continue;
     const score =
       CODE_MATCH_BASE *
       (q.length / keys[i].length) *
@@ -625,6 +644,9 @@ function searchShard(
   opts?: SearchOptions
 ) {
   const { scoreBuf, maskBuf, aliasBuf, fuzzyBuf } = s;
+  // codetype filter: skip the whole shard when none of its systems qualify
+  const allowed = allowedCodetypes(s, opts);
+  if (allowed && allowed.size === 0) return;
   const N = s.docCount;
   const fullMask = (1 << qTokens.length) - 1;
   let touchedCount = 0;
@@ -732,7 +754,11 @@ function searchShard(
   }
   for (let i = 0; i < touchedCount; i++) {
     const d = s.touched[i];
-    if (maskBuf[d] === fullMask && (!billable || billable[d] === 1)) {
+    if (
+      maskBuf[d] === fullMask &&
+      (!billable || billable[d] === 1) &&
+      (!allowed || allowed.has(s.docCodetype[d]))
+    ) {
       const lenNorm = 1 / (1 + 0.25 * Math.max(0, s.docLen[d] - 1));
       // usage prior: frequently-used codes surface above obscure ones with
       // equal text relevance (docPrior is log-quantized usage, 0-255)
diff --git a/src/components/CodeLookup/index.ts b/src/components/CodeLookup/index.ts
index 816475e6..aef7a382 100644
--- a/src/components/CodeLookup/index.ts
+++ b/src/components/CodeLookup/index.ts
@@ -5,6 +5,7 @@ export {
   CodeLookup,
   type CodeLookupProps,
   type CodifyDomain,
+  type CodetypeOption,
 } from './CodeLookup';
 export {
   searchShards,